Fluid pressure brake



Sept. 8, 1936. c. A. CAMPBELL FLUID PRESSURE BRAKE Gttornegg Patented Sept. 8, 1936 UNITED STATES v 2,053,461 'FLUID PRESSURE BRAKE- Charles A. Campbell, Watertown, NY., assgnor to The New York Air Brake Company, a corporation of New Jersey Application June 18,

Claims.

This invention relates to air brakes. The purpose of the invention is to pro-vide a simple mechanism applicable to straight air systems which y functions to hold the brake applied irrespective 5 of the position .of the engineers .brake .valve whenever the system is partially charged or its charge falls below a safe minimum value. The effect is to apply the brakes as the system is being charged until a safe condition for operation of the train is reached, and to apply the brakes automatically if the state of charge of the system at any time falls below this safe value.

Generally stated, the invention contemplates a Valve controlling the exhaust port of the engineers brake valve and functioning in response to main reservoir pressure to connect the exhaust port to atmosphere when main reservoir pressure is above a safe value and to connect the exhaust port to the main reservoir and disconnect it from atmosphere when the charge in the reservoir is below a safe value. The valve which connects the engineers brake valve exhaust selectively to atmosphere and to the main reservoir is conveniently operated by a pressure motor to which uid pressure is admitted .or exhausted b-y a Valve of the type known in the air brake art as a protection valve. Y To meet conditions which would exist in lap position of the engineers brake valve the exhaust port ofthe brake valve is connected to the straight air pipe through a check valve'I so that air can iiow from the exhaust pipe to the straight air pipe but not from the straight air pipe to the exhaust pipe. In this way the engineers brake valve is bypassed in lap position to produce an application whenever the state of charge is below a safe value.

The invention is applicable generally to straight air systems and it will be understood that these systems commonly include relay valves, emergency application valves and deceleration controllers. The presence or absence of devices of this sort does not affect the vprinciple of the invention herein claimed, and accordingly it will be described as embodied with the simplest type of engineers brake valve and Vwith a single straight air brake cylinder, such cylinder typifying a straight air brake applying means or system.

In the drawing,- n '50 Fig. 1 isa diagram, chiefly sectional, of a simple straight air system equipped with my invention. The engineers brake valve is shown in release position.

Fig. 2 is a fragmentary section of the engineel-s brake valve showing application position.

1935, serial No. 27,269 (c1. sos-63) Fig. 3 is a sectional View showing lap position.

In the drawing, E represents the main reservoir which is supplied with air under pressure from any suitable source, through the connection .Y l. The main reservoir pipe 8 leads to the pipe bracket and rotary valve seat element 9 of. the engineers brake valve. Mounted on the bracket '9 is a cap It and the pipe 3 delivers main reservoir air to the space within the cap through the connecting passage I I. The rotary valve is shown at I2 and is turned through the usual key I3 by means of the brake valv-e handle I4.

' The straight air pipe I5 connects with the brake cylinder port I5 in the seat of the rotary valve and leads to the straight air brake applying means, which in the drawing is typied by the single brake cylinder Il. The exhaust port in the seatof the rotary valve is indicated at I3 and in the ordinary construction would lead directly to atmosphere.

The rotary valve. I2 has a cavity I9 which in release position (Fig. 1) connects the ports I6 and I8 and thus exhausts the brake cylinder. The valve I2 also has a through port 2I which in service -position (Fig. 2) admits main reservoir air from the space within the cap to the straight air port I6, At such times the exhaust port I8 is blanked. In lap position (Fig. 3) both the ports I6 and. I8 are blanked.

The structure so far described is a conventional representation of a simple straight air system and its operation will be readily understood.'

Connected to pipe 8 are two branches 22 and 23. Branch 22 leads to a chamber 24 in aV valve v Vbody 25. From an adjacent chamber 26 in the body 25 is connected a pipe 21 which is connected with the exhaust port I8 of the brake valve. Between the pipe 2'I and thestraight air pipe I5 is a bypass connection 28 in which is interposed a check valve 29 so arranged as to permit flow toward the straight air pipe I5 Aand prevent flow in reverse direction. Clamped between the member 25 and an intermediate casing member 3| is a combined diaphragm and valve member 32 having an annular rib 33 on its upper face. This diaphragm, in the upper position, indicated in Fig. 1, permitsl free communication between Vthe chambersrt and 26 and consequently at such time connects the main reservoir 6 by way of pipe 22, chambers 24 and 26, pipe 21, port I8, cavity I9 and port Iwith the straight air pipe I5, applying the ybrakes with main reservoir pressure. Under these conditions there may also be flow from chamber 26 by way of check valve 29 and pipe 28 to the straight air pipe I5.

If the rotary valve I2 should be in lap position (Fig. 3) the check valve 29 assures flow to the straight air pipe. At such time diaphragm 32 is held upward by main reservoir pressure, causing the rib 33 to seal and close an exhaust passage leading from the chamber 26 to atmosphere by way of the passage 34, passages 35 and Vent 36.

When the diaphragm 32 is forced downward it disconnects the chambers 24 and 26 and vents chamber 26 by way of 34, 35 and 36. Diaphragm valve 32 thus acts to connect the exhaust pipe 21 of the engineers brake valve selectively with the main reservoir or with atmosphere. To shift fthe diaphragm 32 to perform these functions use is made of a motor diaphragml clampedbetween the member 3| and a cap 38. The diaphragm 31 may be subjected to pressure on its upper 'side by means hereinafter described, and when under pressure reacts through a thrust plate 39 on a stem 4I whichengages kthe diaphragm 32.

The diaphragm 31 is of substantially greater area than 'is the diaphragm 32, so that when it is 'subjected to main reservo-ir pressure it holds the diaphragm 32 downward despite the upward reaction `of main reservoir pressure on the diaphragm 32.

The :branch 23 leads 'to the `end port in the casing I42 of .aso-called protection valve. Mounted in the body of the .protection valve and spaced therefrom is a ycylindrical bushing 43 which is retained by the cap 44 and sealed by gaskets '45 and v46. Slidable in the .bushing y43 is a cupshaped ,piston ITI which is urged ydownward by a coil compression .spring 48. The spring reacts against the lower-end of athrust stem 49 thread- 'ed .in the upper end Vof *the-cap 44 andsealed by a locking cap The lower end ofthe :piston 41 is provided witha rubber seating'face which .coacts with Ya .seat rib 52 formed in bushing V43 and controlling communication withthe pipe 23. .The space within the cap .38 yis connected by pipe 53 with .the annular :space between the body -42 .and the bushing 43. .'Ilhis space communicates with the :'space .at the lower :end of the vpiston 41 .through ports 54 and'with the :space above 'the piston 41 (when the latter is in its `lower position) through ports '55. There is anexhaust passage A56 in the vstem v41%) .and this leads -to atmosphere through v'the passage 151.

When the pressure in the reservoir 6 acting on the end of the .piston 41 within the seat iribi52, is insuicient to overpower the spring -.48,the piston 4:1 :isin its flowermostposition. At such .time .the space above the diaphragm 3.1 .is vented to atmosphere by way of .the annular space around the bushing 43, rports 55, passage 56 and passage 5.1. It follows that the diaphragm 32 is -in its upper Yposition and the .brakes are applied irrespective of the .position of the rotary Avalve I2. The strength of the spring 48 is so chosen that whenpressure in the main reservoir reaches a safe value, the piston 41 will start to move upward against the resistance offered by spring 48. Initial motion Aexposesthe entire area ofthe Vlower end of `vpiston f41 and this piston moves to "its uppermost limit, seating against lthe gasket =46. In -so doing it closes the exhaust from pipe 553 and connects pipes '23 Aand -5'3 together vso that main reservoir air acting on the upperface of the large udiaphragm .31 .forces diaphragm .32 .to its lower position. In so doing it :isolates-.chamber 24 Afromichamber 26 and iconn'e'cts exhaust pipe 21 to atmosphere, as already described. Consequently, if the system is being charged the brakes will be held applied until the pressure in the reservoir 6 reaches a safe value. At that time piston 41 will shift, causing diaphragm 31 to shift diaphragm 32. This cuts off the supply of main reservoir air to the exhaust pipe 21 and connects the exhaust pipe 21 to atmosphere. It follows that vthe brakes will immediately release if the brake valve handle I4 is in release position. If

the brake valve handle I4 is in either application or lap position the brakes may be released :by ymoving lthe valve handle to release position.

As explained, the invention is illustrated as applied to the siniplestLpossible straight air system. It may be'applied inthe same or slightly modied forms to other more complicated straight air .systems without .departing from the spirit of the invention, and this fact is expressly recognized.

What'is claimed is,-

.1. In a fluid pressure brake system, the :combination .of .a lstraight air pipe .a main vreservoir for .supplying pressure -uid to the system; an en- .gineerfs brake Valve having an .exhaust .passage nonnallyleading to atmosphere, :the brake valve being adaptedtoadmitand .exhaust pressure fluid to .and .from the straight air pipe; .means .responsive .t'o main reservoir pressure and effective when .such pressure is below .a .chosen value to disconnect said .exhaust passage from atmosphere and 'connect .it withmain reservoir; and a oneway flow connection `from said :exhaust passage `tosa'id straight air pipe.

`2. In a fluid pressure brake system, the combination of a straight vair pipe; a main reservoir 'for supplying pressure fluidto 'the system; an engineers brake valve having an exhaust passage `normally leading to atmosphere, the brake valve -be'ing adapted'to' admit and exhaust pressure fluid Ito and from the straight air pipe; two-way valve means shiftable to 'connect saidexhaust passage alternatively with `atmosphere and `with -the Vmain reservoir; a motor for shifting the last-named valve means; and ja controller for -said motor responsive to the rise land fall of main reservoir pressure above and below a chosen value.

'3. In fa. `i'luid 'pressure brake system, the combinationof a straight `air pipe; a main reservoir vfor Ysupplying pressure fluid to 'the system; an engineers brake valve 'having an exhaust passage normally leading to atmosphere, the brake 'valve being adapted to `admit and exhaust pressure fluid to and from the straight airpipe; 4two-way valve means 'shiftable'to vconnect said exhaustpassage alternatively with atmosphere and with the main reservoir; a motor for shifting the lastnamed -valve means; a controller for'said vmotor responsive to -the rise and lfall 'of `mainreservoir pressure above Yand below a chosen value; anda one-way ilow connection'from said exhaust passage 'to said straight airpip'e.

Thecombination 'dened in claim 2in which the two-way valve means comprises `a vflexible diaphragm andthe motor comprises a larger ilexible diaphragm.

-5. 'The'c'ombination 'defined in 'claim 2 in'which the two-Way'va1ve=means comprises a flexible diaphragm, the motor comprises a larger flexible diaphragm, and the controller is aprotection valve subject tomain reservoir -pressure land serving in response thereto to subjectithe .motor diaphragm alternately lto main reservoir and atmospheric pressures. Y

.CHARLES A. CAMPBELL. 

